Improvement in safety-valves



lINrrn STATES rricn.,

A'rENT NVIPROVEM ENT IN SAFETY-VALVES.

. Specification forming part of Letters Patent N0. 55, R27, dated May 29, 1866.

To all whom it may concern:

Beit known that I, ADDISON Low, of the city of Albany, in the county of Albany and State of New York, have invented a certain new and useful Improvement in Safety-Valves for Steam-Boilers; and Idohereby declare that the following is a full and exact description of the same, reference being had to the accompanying drawings, and t0 the letters of reference marked thereon, in which- Figure l is a plan view, and Fig. 2 a vertical sectional view taken through the center of the width of the apparatus.

The object of my invention is to produce a safety-valve that will be operated with alarge area ot' the valve with a limited amount ot' weight or pressure applied to the valve in the proportions of the valve and the weight or pressure applied to control its movement and operation; and my invention consists in combining with the safety-valve a measuringvalve,77 by which the action ofthe safety-valve is controlled and governed.

As is well known to engineers, the ordinary safety-valve ot' proper area to relieve the boiler to which it is attached from an overpressure requires a large amount of weight or pressure upon the valve in the proportion of the area ofthe valve to the pressure of the steam to be carried upon the boiler, this weight or pressure, in the case of a large valve, amounting to a sum so large as to stick the valve to its seat sufciently to require a considerable increased pressure of steam to raise it.

My invention is intended to produce the same effect-viz., the opening of the safetyvalveby a greatly decreased amount of weight as proportioned to the size of the safety-valve, so that this objection is entirely overcome.

As shown in the drawings hereunto attached, A is a metal base, fitted with a nozzle, B, to be attached either directly to the top part of the boiler or to a branch pipe on the steamdrum or steam-chimney of the same. In this base is cast or formed suitable steam-channels or passage-ways, as hereinafter mentioned. Upon the upper face of the base-plate A, directly over the nozzle B, is attached and placed the safety-valve seat C containing the safetyvalve D. This valve opens downward-that is, against the pressure of steam--and is so constructed that when it 1s opened or removed from its seat the whole area of the seat of the valve, minus the space occupied by the lugs or steadiments thereof', is opened for the passage of the escaping steam. At the opposite end ofthe base-plate is placed the cylinder E, having wit-hin it the piston F, properly connected through the lever G with the safetyvalve D. At an intermediate point between the safety-valve D and the cylinder E is placed the measuring-valve H in its seat I.

A steam-channel, 2, is formed in the baseplate to allow the steam to pass through the nozzle B to the measuring-valve H, and a similar channel, (partly in the valve-seat I and partly in the base-plate A,) 3, to allow the steam passing from the measuring-valve to enter the cylinder E beneath the piston F.

The piston F is made of or near the area of the safety-valve D, and the lever Gr has its fulcrum so placed as to produce a power of about three of the piston to one ofthe valve, in order to insure the opening of the valve.

The measuring-valve H is retained in its seat by the lever K, having the weight L upon it, the weight being adjusted to proper position upon the lever to produce the required degree of pressure upon the valve.

Incase the apparatus should be required to be so attached and placed as to be beyond the control of the engineer or party having charge ot' the boiler, the whole of its working parts are to be inclosed within an inclosed case, sealed up, if necessary, so that the adjustment of the valve cannot be changed by him.

In its operation the measuring-valve H is Weighted to the required pressure for the boiler to bear with safety, or for the pressure that may be deemed necessary as a maximum. Until that pressure is exceeded the safety-valve D remains closed to its seat. When that occurs the steam passing through the channel 2 to the measuring-valve H raises that valve, allows the steam to pass through the channel 3 to act upon the piston F, causing the safetyvalve D to be depressed and opened and to remain so until the pressure of steam in the boiler is reduced to the measured point at which the measuring-valve H is set, when the latter-named valve is restored to its seat, and by the absence of pressure beneath the piston F, together with the vacuum created in the cylinder E by the condensation of its contained steam, (aided, if found necessary, by the spring 3. The combinationof the piston F, lever G, 5,) the safety-valve D is returned to place und and safety-valve D, es and for the purpose shuts ofi'l the escape of steam. named.

Whitt I elaini as iny invention, and desire 4. The combination of the measuring-valve to secure by Letters Patent, is- H with the piston F, lever G, and safety-valve 1. The combination of the measuring-valve D, as end for the purpose set forth. H with the piston F, for the purpose herein set forth. ADDISON LOW.

2. The combiuation of the piston F with the Witnesses: safety-valve D and the measuring-valve H, es HENRY C. CARR,

FRANCIS S. LOW.

and for the purpose described. 

